How to Learn Musical Key Signatures

Key signatures indicate the tonality or the key of a musical passage. They are sort of a musical shorthand, where, by indicating a key with its signature, the composer doesn’t have to put accidentals before every note in the music he or she is writing.

We name keys after the pitch that happens to be the most prominent, the one we hear as “home base.” For example, if you are playing or listening to a piece of music and determine that G is the most prominent pitch, the music is in the key of G. Here’s an example:

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Clearly, G is the most prominent pitch here How do we know that? Most obviously, it begins and ends on a G. Actually, however, many musical factors contribute to pitch prominence and we’ll get into that in more detail when we learn about harmony. But for now, all you need to know is that a pitch tends to be the most prominent when one of its scales is the basis of the passage of music in question. In the Haydn excerpt above, all of the Fs are sharp. In other words, all of the pitches being played are from a G major scale. To avoid the cumbersome task of placing an accidental next to every F that occurs, the G major key signature appears at the beginning of the piece and every line of music thereafter to show that every F, regardless of octave is to be played as an F-sharp:

For the key of G major, the sharp symbol always goes on the top line of the treble clef, and the fourth line up of the bass clef:

Key Signatures with Sharps

Now, do you remember the tetrachord method for learning the major scales? For each subsequent scale, a fifth higher than the previous one, a sharp is added on . Key signatures work exactly the same way. Notice that F-sharp is of G major. Now we’ll go to the next major scale, D major, which begins on of G major. And remember, you have to make sharp (C-sharp) to get a D major scale. Here is the D major key signature:

For the sharp key signatures, you always know what key it is indicating because the last sharp of the signature is always of that key. Here’s another way to think about it: when you see a key signature with sharps:

Go up a half-step from the last sharp, and that is the name of the major key.

Let’s do one more sharp key signature, A major, and I’ll show you what I mean with a picture:

If this makes sense to you, all that’s left for the sharp major key signatures is to learn the placement on the staff. Here are all of the sharp major key signatures:

From one key signature to the next, the sharps are added in the following order:

F-C-G-D-A-E-B

Each subsequent sharp is a fifth higher than the preceding one. Since the major scales for these key signatures are a fifth apart, it makes sense that each new sharp is a fifth apart as well. As with the lines and spaces of the staff, there are mnemonics for memorizing the order of sharps in key signatures. But again, I believe the best way is just to memorize the order; there are only seven letters. Plus, by simply memorizing the order, you also are learning that each pair of letters represents a fifth, and as I’ve said before, the fifth is the foundation interval of our musical system. (There is much more to learn about the fifth.)

Key Signatures with Flats

We have to learn the flat key signatures differently from the sharp ones, but it’s easy: when you see a key signature with flats:

The next to the last flat is the name of the major key.

Obviously this doesn’t work for the key signature with one flat, which is F. But for the rest of the flat key signatures, take note that the second to the last flat is the name of the major key:

The order of the flats that are added for each key signature is:

B-E-A-D-G-C-F

The reverse order of how the sharps are added!

The Circle of Fifths

Let’s put everything together, the major scales, the key signatures and the fifth relationships. The diagram below is the famous circle of fifths. It’s a great way to learn the key signatures, and as we shall see, the circle of fifths is the basis for much of the structure of tonality. And for those of you who are ahead of the game, I haven’t forgotten the minor scales and keys and their relationship to all this. We’ll get there soon!

You can download a pdf version of the circle of fifths chart here.

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The excerpt used for the example above is from the second movement of Joseph Haydn’s String Quartet in C Major, Op. 76, No. 3. You can download the mp3 version of this beautiful piece from Amazon.com here: